That’s correct, we only support ARM at this time. If you look at the commit log, we have started X86 but it is not functional.
I presented Fracture at the LLVM DevMtg last November. I would not be opposed to upstreaming, but I am not sure it is the right thing for the community as decompiling and compiling are focused on different problems.
What is more likely is to submit patches or help in other mutually beneficial ways. For example, I am working with Renato to write documentation on the DAGISel TableGen backend.